The invention pertains to a process for the coating of eyeglass lenses in a vacuum apparatus.
Eyeglass lenses are provided with one or more layers to make them antireflective and/or to give them certain reflecting colors, which may also be subject to changes of fashion. Eyeglass lenses of plastic are provided with scratch-resistant protective layers to prolong their life.
U.S. Pat. No. 5,138,974 discloses coating eyeglass lenses in batches by attaching a plurality of them to a dome-shaped substrate holder and by coating them by means of a vapor deposition process. In this process, a relatively large number of eyeglass lenses is produced, all of which are provided with the same coating materials. Because of the nonuniform way in which the vapor spreads out from the coating source, however, it is practically impossible to provide all of the eyeglass lenses of one batch with layers of the same thickness. Aside from this problem, batch-wise systems of this type cannot be integrated into the normal production sequence of modern lens production systems, in which eyeglass lenses are produced individually or in pairs and then subjected to further processing. Eyeglass lenses are usually produced "by prescription" in pairs with the same properties; and also in this respect the known batchwise systems are inflexible, since they are incapable of producing a succession of eyeglass lenses which differ from one another with respect to their radii of curvature and coating materials.
A further disadvantage of the known batch systems consists in that the eyeglass lenses must be loaded by hand onto the dome-shaped substrate holders. This hand loading brings with it the danger of damage. It is not possible in practice to automate this step.